Nonviscous aqueous dispersion compositions of water-swellable layered silicates and the method of producing the same

ABSTRACT

Concentrated suspensions of smectite clays are obtained as either relatively “thin” or highly shear-thinning slurries that are easy to pump, by adding one or more of certain cationic polymers whose weight average molecular weight, Mw, is 50,000 or higher. It was found during the course of the invention that a cationic polymer with an Mw of 10,000 did not work, while the same polymer with a bimodal Mw of 50,000 and 30,000 worked satisfactorily. To achieve the full advantage of the present invention, the cationic polymer preferably has 1 to 10 milliequivalents of cationic charge per gram of the polymer, and more preferably 5 to 10 milliequivalents of cationic charge per gram of the polymer, and most preferably 6 to 8 milliequivalents of cationic charge per gram of the polymer.

SUMMARY OF THE INVENTION

This application is a continuation of U.S. patent application Ser. No.10/706,752, filed Nov. 12, 2003, which is based on U.S. ProvisionalPatent Application 60/425,862, filed Nov. 12, 2002.

The present invention relates to concentrated, aqueous dispersion oraqueous slurry compositions of water-swellable layered silicates such asthe smectite clays, which either have unusually low viscosities or havehigh shear-thinning properties, as well as the ability tocoagulate/flocculate suspended materials in water, and a method ofproducing the compositions. While the weight content of the suspendedclay particles in these slurry compositions can be as high as 40-50%,the dispersions remain sufficiently thin or shear-thinning to allowpumping of the slurry. Ordinarily, even at relatively low concentrations(for example 5-10%), smectite clays can bring about significantthickening in aqueous suspensions, often turning the suspensions intogels.

A key object of the present invention is to produce such dispersions ofsmectite clays, which are amenable to pumping even when the clay contentis relatively high, in a manner that renders the dispersion compositionsespecially suited for coagulating/flocculating suspended matter inwastewater or other water streams. This is achieved by adding one ormore cationic polymers with a weight average molecular weight of atleast 50,000 Daltons to aqueous clay suspensions, at concentrationssufficient for the cationic polymer(s) to function as a thinning agentfor the suspended clay particles.

Thickening or gelation of aqueous suspensions by smectite clays is amanifestation of clay particles forming a network structure due tointerparticle associations, that spans through the entire suspensionvolume, entrapping the suspension medium. A thinning agent acts tominimize such particle-to-particle links by providing for interparticlerepulsion upon adsorption on the particle surface. The use of a cationicpolymer as a thinning agent leaves the surface of the clay particlescationic such that these cationic particles can draw anionic particlesinto coagulation/flocculation by bridging two or more of such particlesthat generally constitute the suspended matter in water streams.

BACKGROUND OF THE INVENTION

Layered silicate materials such as the smectite clays are a class ofinorganic particulate materials that occur as stacks of individual,planar silicate layers referred to as platelets in the clay literature.Examples of smectite clays include montmorillonite, bentonite, bidelite,hectorite, saponite, and stevensite. These clays are popular particulategellants or thickeners for aqueous compositions.

Smectite clays also find use as a flocculation aid in wastewatertreatment where the flocculant compositions used are generally solidadmixtures of clay and other treatment reagents. These flocculantproducts, however, are excluded from those wastewater treatmentscenarios where the facility is not equipped to handle any solidtreatment reagent. Since smectite clay-water slurries turn into gelsonce the clay content exceeds a level that may be as low as in the rangeof 5-10% by weight, handling, especially pumping, of clay suspensionswith high clay content may prove to be extremely difficult, if notimpossible. Nevertheless, in order for it to be viable, any liquidproduct of clay-based flocculants should have clay content muchexceeding the above range. The present invention reveals a method forachieving such desirable liquid products of smectite clay-basedflocculants, and the compositions thereof.

The face-surfaces of the platelets of smectite clays bear anioniccharges counterbalanced by exchangeable cations that remainelectrostatically attracted to the anionic charge of the clay surface.The exchangeable cations are generally either sodium ions or calciumions. Smectite clay is referred to as sodium or calcium clay, dependingon the type of predominant counterions associated with the face-surfacesof the clay platelets. While the anionic charge on the plateletface-surfaces does not vary with pH, the electrical charge on theedge-surfaces of these clays, although anionic under alkaline pH, couldbe cationic under acidic pH.

Fundamentally, the formation of particulate gels is a manifestation ofsuspended colloidal particles forming a network structure that entrapsand thus immobilizes the suspending medium. Clay-based gels may formwhen individual platelets or stacks of a few, e.g., 3-15, aggregatedplatelets (tactoids) engage in interparticle associations with theirneighboring platelets. These particle-to-particle links result in aparticulate structure pervading through the entire suspension-volume.Such interparticle associations are governed by the interplay betweenthe attractive and repulsive forces that generally act between particlessuspended in a liquid.

Clearly, the strength of particulate gels will depend on the number ofinterparticle associations in a given volume of the gel, implying thatthe greater the number-concentration of suspended particles, thestronger is the gel. Also, a dominance of the attractive interactionsover the repulsive interactions, the likelihood of which increases withdecrease in interparticle separation distance, is required for suspendedparticles to associate with their neighbors. An increase innumber-concentration of particles will tend to reduce their separationdistances, an effect that could be especially dramatic for planarparticles since the separation distance between two adjacent plateletswill vary along their lengths when their faces do not align in parallelconfiguration. Nonetheless, too strong an attraction between adjacentclay platelets may draw them into strong face-to-face association,minimizing the number-concentration of particles.

Considering the above, the key to making clay-based gels is to ensurethat there is sufficient interplatelet repulsion for the clay plateletsto exfoliate (delaminate) under shear, releasing a large number ofplatelets as individual platelets or tactoids having fewer stackedplatelets, that would then be available to form a particle network. Onthe other hand, in order to form a voluminous network structure, the netinteraction (the sum of attractive and repulsive forces) between thedelaminated platelets must be such that they can remain “bound”(attracted) to their neighboring platelets without being drawn intostrong face-to-face association. Accordingly, the gel-network may formif the delaminated platelets, while being separated from the surroundingplatelets by as thick as possible an intervening layer of the suspendingmedium, reside in a minimum of free energy of interaction with theneighboring platelets. Albeit physically separated from their neighbors,the individual platelets are no longer free to move independently, beingtrapped in a free energy minimum, in effect producing a particulatestructure, and therefore thickening or gelation. Yet another phenomenonthat clay-based gels may form in aqueous compositions, is where clayplatelets coagulate due to edge-to-face associations, forming theso-called “card-house” structure described in clay literature.

The sodium smectite clays exfoliate to a much greater extent than theircalcium analogs. For this reason, the sodium smectite clays produce asignificantly higher level of thickening as compared to the calciumsmectite clays. Therefore, one way of having concentrated claysuspensions with high fluidity is to use calcium smectite clays.However, such dispersions, while possibly meeting the requirement of lowviscosity, would not present a high number concentration of delaminatedplatelets, which may be desirable for having good flocculatingproperties during wastewater treatment.

The ability of clay platelets to bring about coagulation/flocculation ofsuspended debris particles in wastewater is related to a phenomenon thatmay be described as heterocoagulation (coagulation between dissimilarmaterials) between the clay platelets and the debris particles. Suchheterocoagulation would occur when the physicochemical conditions of thewastewater are such that the interaction between the debris particlesand the clay platelets is attractive, even though the interactionbetween the debris particles is repulsive, preventing these particlesfrom coagulating. Another way to describe such a heterocoagulationprocess is to use the analogy of bridging flocculation by polymericflocculants, as described in colloid literature: like polymericflocculants, the clay platelets draw the suspended debris particles intoflocculation by sticking to and thus bridging two or more debrisparticles simultaneously.

It may be expected that the aforementioned debris-clay coagulationprocess will be favored if the number concentration of clay platelets ishigh (i.e., if the clay platelets are highly delaminated or exfoliated,an effect that also promotes thickening induced by clay platelets)and/or if a strong clay platelet-debris particle attraction is broughtinto play. Accordingly, conflicting demands are faced in obtainingconcentrated, non-viscous clay-suspensions where the clay platelets aresufficiently delaminated in order to have good flocculating power.Nevertheless, even when a large number of clay platelets have beenreleased due to exfoliation, the platelets may be prevented fromengaging into any association with the neighboring platelets if theinterparticle repulsive forces greatly dominate over the attractiveforces. Therefore, the key to attaining concentrated, but non-viscousclay-suspensions, without necessarily sacrificing good exfoliation ofclay platelets, is to ensure that strong repulsive forces act betweenthe platelets, superseding any attractive interplatelet forces that tendto bring about associations between the platelets. Most surfaces tend toacquire an anionic charge when wetted with an electrolyte or water.Also, the surface active agents (emulsifiers and dispersing agents) thatare more commonly used in industrial applications are anionic, resultingin suspended particles in most wastewater streams that are generallyanionic. So in the context of clay-based flocculants, it has been foundthat a way to increase the clay platelet-debris attraction is to renderthe surface of the clay platelets cationic through the adsorption ofcationic species.

As described in colloid literature, ionic polymers or polyelectrolytesmay provide for electrical and steric repulsion forces between suspendedparticles, if, upon adsorption on the particle surface, i) the adsorbedpolymer chains render the particle surface electrically charged, ii) theadsorbed polymer chains occupy more than 50% of the particle surfacearea, and iii) the polymer segments dangle out off the particle surfaceinto the surrounding dispersion medium, forming loops and tails. Oncebrought into play, these repulsion forces act to minimize interparticleassociations, resulting in thinning of the suspension. The adsorption ofcationic polyelectrolytes on the surface of clay platelets couldpotentially increase the attractive interaction between the clayplatelets and the anionic debris particles, which in turn could enhancethe flocculating ability of clay.

Although the prior art teaches the use of various types of anionicpolymer as thinning agents for smectite clay suspensions, it does notdisclose the effects of cationic polymers on the rheological properties(for example, viscosity properties) of concentrated clay suspensions(for example, suspensions having a smectite clay content exceeding 20%by weight). Therefore, it is not clear whether or not the addition of acationic polymer to a concentrated suspension of smectite clay wouldproduce either a “thin” or a highly shear-thinning suspension that showsa viscosity significantly lower than what it would have been in theabsence of the polymer. It is only since the present invention that ithas been found that cationic polymers with a weight average molecularweight falling within a certain range, when used even at relatively lowconcentrations, would render a concentrated suspension of smectite claysnon-viscous, while the suspension shows considerable flocculatingability.

Although a targeted application for the product of the present inventionis coagulation/flocculation of suspended matter in water streams as, forexample, in wastewater treatment, because of the coagulating ability ofthe product, it may be used even as a drainage aid in the papermakingprocess, wherein the product helps in bringing about agglomeration ofpulp fibers to facilitate the drainage process.

Other potential uses of the product include, but are not limited to, anadditive in personal care and cosmetic formulations, as well as a fabricsoftener. The cationic polymer-modified clays would be substantive to(or adhere onto) the anionic surfaces of the hair or the skin, such thatthese clays can help deliver some useful hair care or skin careproperties when used as an additive in personal care or cosmeticproducts. For example, the deposition of cationic clay platelets on theanionic surface of the hair shafts is expected to be substantive to hairshafts to enhance hair styling. Accordingly, the use of cationicpolymer-modified clays in hair care products should add to the hairstyling properties of these products. The prior art discloses the use ofsmectite clays as a fabric softener. Furthermore, the most commonly usedfabric softeners are cationic surfactants. As for the molecularstructure, surfactant molecules contain a hydrophilic part and ahydrophobic part, with the two parts of the molecule segregated from oneanother. The cationic surfactants used as fabric softeners impartsoftness by adsorbing onto the (negatively charged) fabrics with theirhydrophilic part, consisting of the cationic functional group, attachedonto the fabric surface, while their hydrophobic part projects outwardlyfrom the surface. Such adsorption of the cationic surfactants minimizesinterfacial tension between the fabric surface and the surrounding airmass and minimizes the adhesion of water to the fabric surface. Thisreduces the shrinkage (reduction of substrate surface area) andresulting hard “feel” that accompanies the removal of water from thesubstrate. In accordance with the present invention, the cationicmodification of the smectite clay surface by the surface treatment ofthe clay with one or more cationic species, e.g., polymers, that containone or more hydrophobic groups, render the clay platelets betterequipped to serve as a fabric softener.

SUMMARY OF THE INVENTION

The objects of the present invention are as follows:

-   -   Produce concentrated suspensions of layered silicate materials,        that are amenable to pumping, and show good        coagulating/flocculating abilities by surface treating the        layered silicate material with cationic polymers.    -   Provide a method for surface-treating particles of layered        silicate materials, that would result in thinning of        concentrated suspensions of these particulate materials, while        rendering the particles better equipped to function as a        coagulant/flocculant    -   Produce a surface-modified clay wherein the clay surface is        rendered cationic due to the surface-treatment of the clay with        one or more cationic polymer(s), in order that such        cationically-modified clays are useful in formulating hair and        skin care products as well as a fabric softener

Preferably, the weight content of the layered silicate material in thesuspension is more than 25%, and the weight ratio of the silicatemineral and the thinning reagent is 4:1 to 10:1. Since one of thetargeted application areas, i.e., wastewater treatment, for the productof the present invention, is highly cost-sensitive, it is important thatthe dosage level of the thinning agent is held relatively low.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred layered silicate materials are phyllosilicates of the 2:1type with an anionic charge on the face surface, counterbalanced bysodium counterions. More preferably, the layered silicate materials aresmectite clays such as montmorillonite, bentonite, bidelite, hectorite,saponite, and stevensite.

According to the present invention, concentrated suspensions of smectiteclays are obtained as either relatively “thin” or highly shear-thinningslurries that are easy to pump, by adding one or more of certaincationic polymers whose weight average molecular weight, Mw, is 50,000or higher. It was found during the course of the invention that acationic polymer with an Mw of 10,000 did not work, while the samepolymer with a bimodal Mw of 50,000 and 30,000 worked satisfactorily. Toachieve the full advantage of the present invention, the cationicpolymer preferably has 1 to 10 milliequivalents of cationic charge pergram of the polymer, and more preferably 5 to 10 milliequivalents ofcationic charge per gram of the polymer, and most preferably 6 to 8milliequivalents of cationic charge per gram of the polymer.

The word “thin” above refers to such slurry consistency or viscosity asexemplified by the Brookfield RV viscosity (at 10 rpm) of a suspensioncontaining 38% of a sodium smectite clay (based on the total weight ofclay and water, the dispersion medium), and under strong agitation by,for example, a shaft-mounted agitator, is less than 6,000 cps, morepreferably less than 1,000 cps, and most preferably less than 500 cps.The clay content of the concentrated suspensions of the presentinvention, expressed as a percentage of the total weight of clay andwater (dispersion medium), is in the range of 1-50%, more preferably inthe range of 5-45%, and most preferably in the range of 25-45%. Thedosage of the cationic polymer based on the dry weight of clay is in therange of 0.1-50%, more preferably in the range of 8-30%, and mostpreferably in the range of 10-25%.

According to one embodiment of the present invention, the smectite clayis surface-treated with a mixture of low and high molecular weightcationic polymers, wherein the weight average molecular weight of thehigh molecular weight cationic polymer is at least 50,000. When suchmixtures of cationic polymers are used, the weight ratio of the lowmolecular weight polymer to the high molecular weight polymer is in therange of 10:1 to 1:10, more preferably in the range of 7:1 to 1:7, andmost preferably in the range of 1:1 to 1:7.

An important embodiment of the present invention is that theconcentrated suspension of cationic polymer-modified layered silicatematerials shows coagulating/flocculating abilities either by itself orin conjunction with one or more additional anionic or cationic polymersthat are commonly used as a flocculant. By the phrase“coagulating/flocculating ability” is meant the ability to significantlyincrease the clarity or reduce the turbidity of a water stream thatcontains suspended matter, by inducing aggregation of most or all of thesuspended matter, forming aggregated particles or flocs, for easyseparation from the water.

The most preferred cationic polymers that can be used in producing thin,concentrated suspensions of layered silicate materials include but notlimited to poly (diallyldimethylammonium chloride) referred to herein aspoly(DADMAC), polyquaternary amine polymers prepared fromepichlorohydrin and dimethylamine referred to herein as EPI/DMA, andtheir copolymers with non-ionic, water-soluble polymers. Cationicpolymers having weight average molecular weights of 50,000 or higher,derived from natural polymers such as tannin, starch, proteins, guar,gum, lignin, lignosulfonate, and humate can also be used. Polyalkylamines or polyaryl amines having a weight average molecular weight of atleast 50,000 can be used as well. For use in personal care and cosmeticproduct formulations, any cationic polymer with a weight averagemolecular weight of at least 50,000, including various cationiccopolymers that are used in hair and/or skin care products may beuseful. Film forming cationic polymers (for example, chitosan polymersor copolymers; cationic polymers or copolymers containing polyvinylpyrrolidone; polyacrylate; and polyalkylmethacrylate); cationic polymersor copolymers containing hydroxyl, carboxyl, carbonyl, phenolic, and/orether groups; as well as cationic polymers or copolymers that contain astrong hydrophobic moiety such as an alkyl chain of C8 or higher, andone or more aromatic groups may be used when the product of the presentinvention is used in personal care and cosmetic formulations.

In accordance with another embodiment of the present invention, thedispersions of cationic polymer-modified clay further contain one ormore coagulation/flocculation aids such as a salt of monovalent, andpreferably multivalent, cations such as aluminum, iron, and calcium.

For wastewater treatment, the dosage of the product of the presentinvention, based on the sum of the weights of the dry clay and the drycationic polymer, could be in the range of 1 ppm-10,000 ppm, morepreferably in the range of 10 ppm-1000 ppm, and most preferably in therange of 10 ppm-500 ppm. For the fabric softening application, theproduct dosage, based on the sum of the weights of the dry clay and thedry cationic polymer, could be in the range of 0.005%-30% of the totalweight of the fabric softener formulation, more preferably in the rangeof 1%-20%, and most preferably in the range of 1%-10% of theformulation. A detergent product that may contain the product of thepresent invention as a fabric softener component of the formulation maybe eventually used in a diluted form, for example, as encountered in awash cycle of a commercial washer. For hair and skin productformulations, the dosage of the product of the present invention, basedon the sum of the weights of the dry clay and the dry cationic polymer,could be in the range of 0.005%-10% of the hair or skin care productformulation, more preferably 0.005%-5% of the formulation, and mostpreferably 1%-5% of the formulation. Since hair and/or skin careproducts generally contain a vehicle or a solvent, the solventcomposition should contain at least 20% by weight of water, in order toget the full benefit of the present invention.

In the present invention, the thin, concentrated suspensions of layeredsilicate materials are produced by adding a single layered silicatematerial, or a mixture of layered silicate materials to an aqueoussolution of one or more of the aforementioned types of cationicpolymers, and then shearing the resulting suspension using a shearingdevice such as a shaft-mounted shearing agitator, a rotor-statormixture, a homogenizer, a media mill, or a colloid mill for a period oftime to at least partially exfoliate the layered silicate material(s).

In order to illustrate the present invention clearly, the followingexamples and data are presented. However, they should not be construedas limiting the scope of the invention to their details.

EXAMPLE 1

This example shows the thinning ability of poly(DADMAC) (ZETAG 7131,weight average molecular weight, Mw=100,000, obtained from CibaSpecialty Chemicals) in concentrated suspensions of smectite clay. Theprocedure followed in carrying out the slurry-viscosity tests forevaluating the cationic polymer is as follows: 76 grams of a sodiumsmectite clay (ACCOFLOC obtained from CETCO/AMCOL International andPOLARGEL NF obtained from ACC/Amcol International) was slowly added toan aqueous solution of the cationic polymer, and sheared in amulti-speed Waring blender, while the blender was operated at speed 1.Immediately after the entire amount of clay was added, the resultingslurry was homogenized at speed 7 (22,000 rpm) of the blender for 5minutes. The suspension thus produced was transferred to a plasticcontainer and the viscosity was measured in a Brookfield RV viscometer.The slurry-viscosity was measured after 20-25 minutes from the time ofcompletion of mixing, at shear rates corresponding to 10, 20, 50, and100 rpm of spindle speed in a Brookfield RV viscometer. After completionof viscosity measurements, the lid of the slurry container was replacedand the suspension was shaken vigorously by hand for a brief period oftime, after which the slurry viscosity was measured again at 10 rpm. Theresults of the slurry viscosity tests are shown in Table I. TABLE IViscosity Time Since after Completion Brookfield Manual Cationic Tap ofMixing, Viscosity, Shaking, Test # Clay Polymer, g Water, g minutes Rpmcps cps 1 ACCOFLOC 27.14 106.46 20 10 350 75 ZETAG 7131 20 250 (35%solids) 50 178 100 159 2 ACCOFLOC 32.57 102.93 20 10 120 60 ZETAG 713120 115 50 108 100 110 3 POLARGEL 21.71 109.99 20 10 12,000 2,000 NFZETAG 7131 20 6,750 50 3,000 100 1,775 4 POLARGEL 27.14 106.46 20 104,200 475 NF ZETAG 7131 20 2,350 50 1,080 100 660 5 POLARGEL 32.73102.83 20 10 4,400 475 NF ZETAG 7131 20 2,550 50 1,300 100 800

It should be noted that the slurries from tests 3 through 5 thickened upto the consistency of a gel after about 16 days of standing. However,upon shaking the slurry containers vigorously by hand for a brief periodof time, the suspensions from tests 4 and 5 showed high shear thinning,with 890 cps and 750 cps, respectively, being their Brookfieldviscosities at 10 rpm.

EXAMPLE 2

This example shows the efficacy of EPI/DMA (SUPERFLOC C-573 Flocculant,bimodal weight average molecular weight, Mw=50,000 and 30,000, fromCytec Industries, and ZETAG 7191, weight average molecular weight,Mw=50,000, from Ciba Specialty Chemicals) as a thinning agent inconcentrated sodium smectite clay suspensions, based on slurry viscositytests. The procedure followed in carrying out the slurry-viscosity testsis the same as that described in EXAMPLE 1. The results of the slurryviscosity tests are shown in Table II. TABLE II Time Since ViscosityCompletion Brookfield after Cationic Tap of Mixing, Viscosity, Shaking,Test # Clay Polymer, g Water, g minutes Rpm cps cps 1 ACCOFLOC 19 114.623 10 3,000 Viscous C-573 (50% 20 1,375 solids) 50 900 100 580 2ACCOFLOC 22.8 112.7 20 10 700 40 C-573 20 500 50 240 100 190 3 ACCOFLOC26.6 110.8 20 10 260 12 C-573 20 165 50 95 100 69 4 ACCOFLOC 22.8 112.730 10 3,700 40 ZETAG 20 1,300 after about 6 7191 50 480 hours from 100390 the time of mixing

EXAMPLE 3

This example shows that cationic reagents having a relatively low weightaverage molecular weigh would not work well as thinning agents forconcentrated suspensions of sodium smectite clay. The cationic reagentsevaluated include SUPERRFLOC C-572 Flocculant (Mw=10,000, from CytecIndustries), and AGEFLEX (monomer for the DADMAC polymer from CibaSpeciality Chemicals). Slurry viscosity tests were carried out the sameas in the previous examples. TABLE III Time Since Viscosity CompletionBrookfield after Cationic Tap of Mixing, Viscosity, Shaking, Test # ClayPolymer, g Water, g minutes Rpm cps cps 1 ACCOFLOC 22.8 112.7 30 1010,800 C-572 (50% 20 5,350 solids) 50 2,760 100 1,320 2 ACCOFLOC 30.4108.9 35 10 4,300 5,250 C-572 20 2,875 50 1,360 100 750 3 ACCOFLOC 38105.1 20 10 4,100 3,300 C-572 20 2,300 50 980 100 530 4 ACCOFLOC 27.14115.96 20 10 4,200 2,700 Ageflex 20 2,400 (70% solids) 50 1,860 100 1020

EXAMPLE 4

This example shows the slurry thinning ability of mixtures of cationicpolymers, ZETAG 7131, with Mw=100,000, and ZETAG 7122, with Mw=425,000,in a concentrated suspension of sodium bentonite clay. Similarslurry-viscosity tests as in the previous examples were carried out.TABLE IV Time Since Viscosity Completion Brookfield after Cationic Tapof Mixing, Viscosity, Shaking, Test # Clay Polymer, g Water, g minutesRpm cps cps 1 ACCOFLOC 32.57 102.93 20 10 120 60 ZETAG 7131, 20 115 15%polymer 50 108 on clay 100 110 2 ACCOFLOC 57 78.5 20 10 19,750 17,500Zetag 7122, 20 14,375 15% polymer 50 9,460 on clay 100 6,940 3 ACCOFLOC16.29 113.41 20 10 Highly ZETAG 20 viscous 7131, 7.5% 50 polymer on 100clay 4 ACCOFLOC 28.5 101.2 20 10 Highly ZETAG 7122, 20 viscous 7.5%polymer 50 on clay 100 5 ACCOFLOC 28.5 90.61 20 10 1,500 700 ZETAG7122 + 16.29 20 1,300 ZETAG 7131, 50 1,100 15% polymer 100 940 on clay 6ACCOFLOC 76 ZETAG 58.97 20 10 4,250 7122 + 6.51 20 3,700 ZETAG 7131, 503,120 23% polymer 100 2,760 on clay

EXAMPLE 5

This example shows the coagulating/flocculating ability of aconcentrated suspension of sodium smectite clay, wherein poly(DADMAC) isused as the thinning agent for the slurry. The clay suspension isidentical in composition to the clay suspension in Test 1 of EXAMPLE 1.Flocculation tests were carried out by adding a given weight of the claysuspension to 100 grams of an industrial wastewater sample having poorclarity or high turbidity. In some cases, a measured amount of a 15%alum solution was added to the wastewater sample along with the claysuspension. After mixing (using a magnetic stirrer) the clay suspensionand/or the alum solution with the wastewater for 1 minute, an aliquot ofa dilute solution (0.1%-1% by weight) of an anionic flocculant (sodiumpolyacrylate) marketed under the trade-name of F730A by CETCO was addedto the wastewater, and mixing was continued for an additional 1.25minutes during which time the suspended materials contained in thewastewater separated out as large flocs. The treated wastewater thusobtained was filtered, and the filtrate was taken for % Transmittance (%T) measurement (at 620 nm wavelength) in a Hach Spectrophotometercalibrated with deionized water for 100% T. A high value of % Tindicates a high level of clarification or a low level of turbidity.TABLE V Wastewater Clay 15% Alum Anionic Test # sample ID Suspension, gsolution, g polymer, g pH % T Comments 1 Thomas Betts 0 0.3 6, No 0.1%clarification solution of F730A 2 Same as 0.25 0.3 6, 7.39 94 above 0.1%solution of F730A 3 Same as 0.3 0.35 6, 7.18 95 above 0.1% solution ofF730A 4 Same as 0.35 0.3 6, 7.86 97 above 0.1% solution of F730A 5Muellor 0.3 0.3 0.28, 8.99 97 Vibratory 1% solution of F730A 6 Muellor0.3 0 0.3 9.09 98 Vibratory 1% solution of F730A

EXAMPLE 6

This example shows the coagulating/flocculating ability of sodiumbentonite dispersions containing mixtures of cationic polymers, ZETAG7131, with Mw=100,000, and ZETAG 7122, with Mw=425,000. The compositionsof the dispersions tested are given below.

Slurry # 1

ACCOFLOC clay=100 g

ZETAG 7131=22.86 g

ZETAG 7122=22.5 g

Tap water=91.14 g

Slurry # 2

ACCOFLOC clay=100 g

ZETAG 7131=8.57 g

ZETAG 7122=100 g

Tap water=47 g

The dispersions were tested for clarifying ability in a sample of alaundry wastewater. The results of these flocculation tests are shown inTable VI. TABLE VI Clay Suspension, Anionic Test # Slurry # ppm Polymer,ppm % T 1 1 780 10 97 2 2 300 Approximately 94.5 10-30

1. An aqueous suspension comprising a sodium smectite clay, and at leastone water-soluble, cationic polymer with a weight average molecularweight of at least 50,000, wherein the amount of sodium smectite clayexceeds 20 weight percent based on the total weight of the aqueoussuspension, and wherein the aqueous suspension has a Brookfield RVviscosity, at 10 rpm, less than 6,000 cps, when measured at 38% sodiumsmectite clay, based on the total weight of clay and water.
 2. Thesuspension of claim 1 wherein the layered silicate is selected from thegroup consisting of smectite clays, lithium magnesium silicate(laponite), and a mixture thereof.
 3. (canceled)
 4. The suspension ofclaim 1 wherein the amount of sodium smectite clay is from greater than20 weight percent to 50 weight percent based on the total weight of thesuspension.
 5. The suspension of claim 4 wherein the amount of sodiumsmectite clay is from 25 weight percent to 50 weight percent based onthe total weight of the suspension.
 6. The suspension of claim 5 whereinthe amount of sodium smectite clay is from 25 weight percent to 45weight percent based on the total weight of the suspension.
 7. Thesuspension of claim 1 wherein the weight ratio of sodium smectite clayto the cationic polymer is 2:1 to 1000:1.
 8. The suspension of claim 7wherein the amount of cationic polymer in the suspension is in the rangeof 0.1% to 50% based on the dry weight of sodium smectite clay.
 9. Thesuspension of claim 8 wherein the amount of cationic polymer in thesuspension is in the range of 8% to 30% based on the dry weight ofsodium smectite clay.
 10. The suspension of claim 9 wherein the amountof cationic polymer in the suspension is in the range of 10% to 25%based on the dry weight of sodium smectite clay.
 11. The suspension ofclaim 1 wherein the cationic polymer has 1 to 10 milliequivalents ofcationic charge per gram of the polymer.
 12. The suspension of claim 11wherein the cationic polymer has 5 to 10 milliequivalents of cationiccharge per gram of the polymer.
 13. The suspension of claim 12 whereinthe cationic polymer has 6 to 8 milliequivalents of cationic charge pergram of the polymer.
 14. The suspension of claim 1 wherein thesuspension contains a mixture of a lower molecular weight cationicpolymer and a higher molecular weight cationic polymer, at least one ofwhich has a weight average molecular weight of at least 50,000.
 15. Thesuspension of claim 14, wherein the weight ratio of the lower molecularweight cationic polymer to the higher molecular weight cationic polymeris in the range of 10:1 to 1:10.
 16. The suspension of claim 15, whereinthe weight ratio of the lower molecular weight cationic polymer to thehigher molecular weight cationic polymer is in the range of 7:1 to 1:7.17. The suspension of claim 16, wherein the weight ratio of the lowermolecular weight cationic polymer to the higher molecular weightcationic polymer is in the range of 1:1 to 1:7.
 18. A method ofclarifying a wastewater containing suspended matter comprising adding tosaid wastewater an effective amount of the aqueous suspension of claim 1to flocculate or coagulate the suspended matter.
 19. The method of claim18, comprising adding to said wastewater the sodium smectite clay andcationic polymer at a combined dry weight of 1 ppm to 10,000 ppm, basedon the weight of the wastewater treated.
 20. The method of claim 19,comprising adding to said wastewater the sodium smectite clay andcationic polymer at a combined dry weight of 10 ppm to 1,000 ppm, basedon the weight of the wastewater treated.
 21. The method of claim 20,comprising adding to said wastewater the sodium smectite clay andcationic polymer at a combined dry weight of 10 ppm to 500 ppm, based onthe weight of the wastewater treated. 22.-26. (canceled)
 27. A method ofsoftening a fabric comprising contacting said fabric with an effectiveamount of the aqueous suspension of claim
 1. 28. The method of claim 27,wherein the aqueous suspension is diluted with water during fabricsoftening such that the concentration of sodium smectite clay andcationic polymer in said water is in the range of 0.001% to 5% byweight, based on the total weight of water.
 29. The method of claim 28,wherein the aqueous suspension is diluted with water such that theconcentration of sodium smectite clay and cationic polymer in said wateris in the range of 0.005% to 3.0% by weight, based on the total weightof water.
 30. The method of claim 29, wherein the aqueous suspension isdiluted with water such that the concentration of sodium smectite clayand cationic polymer in said water is in the range of 0.1% to 2.5% byweight, based on the total weight of water.
 31. The method of claim 30,wherein the aqueous suspension is diluted with water such that theconcentration of sodium smectite clay and cationic polymer in said wateris in the range of 0.3% to 1.0% by weight, based on the total weight ofwater.
 32. A method of reducing the viscosity of an aqueous suspensionof a having greater than 20 weight percent sodium smectite claycomprising shearing said suspension with a cationic polymer having aweight average molecular weight of at least 50,000, such that the aqueossuspension has a Brookfield RV viscosity, at 10 μm, less than 6,000 cps,when measured at 38% sodium smectite clay, based on the total weight ofclay and water.